Corrosion inhibiting compositions



United States Patent 3,281,369 CORROSION INHIBITING COMPOSITIONS RobertWalter Wynn, Easton, Pa., assignor to General Aniline & FilmCorporation, New York, N.Y., a corporation of Delaware No Drawing. FiledJune 26, 1963, Ser. No. 290,612 9 Claims. (Cl. 252-146) The presentinvention relates, in general, to argano phosphates and, in particular,to tripropargyl phosphate which finds immediate and practical utility asa corrosion inhibitor in lubricating oils, hydraulic fluids, antifreeze,dry cleaning compositions and acid-metal cleaning or pickling solutions.

When operations such as metal cleaning, scale removal and the like arecarried out on an industrial scale, acid solutions are employed toaccomplish the purpose. Acids which find utility in this respect includeinorganic and organic acids, such as hydrochloric, sulfuric, phosphoric,hydrofluoric, citric, oxalic, sulfamic acids, and the like.

In almost all of the aforesaid operations, it is usually necessary toincorporate a corrosion inhibitor into the acid solution to prevent ordecrease the attack of the acid upon the base metal. In order for acorrosion inhibitor to be considered an effective candidate forincorporation into an acid cleaning solution it should, in addition toinhibiting or preventing corrosion of the base metal, function todecrease or inhibit hydrogen embrittlement of the base metal;'be stablewith respect to color and precipitation in acid solutions. However,according to some heretofore customary practices, certain commercialinhibitors which are derivatives of propargyl, alcohol as well aspropargyl alcohol itself, when incorporated into acid cleaningsolutions, have a decided tendency to turn back and form insolublepolymeric precipitates in the solutions. In addition, corrosioninhibition tests of propargyl alcohol and certain propargyl alcoholderivatives indicate that the use of such compounds does not inhibit thechange in crystallinity and hence embn'ttlement of the metal to thedesired degree.

Accordingly, it is an object of this invention to provide a corrosioninhibiting composition which does not substantially change color uponuse.

Another object of the invention resides in the provision of corrosioninhibiting compositions which have a substantially high degree ofstability with regard to precipitation upon standing.

Yet another object of this invention is directed to the feature of acorrosion inhibiting composition which is capable of substantiallypreventing or lessening the phenomenon known as hydrogen embrittlement.

Still other objects of the invention will become more readily apparentfrom the following detailed description of the invention.

The above objects of the invention are readily accomplished byincorporating into acid-cleaning compositions a corrosion inhibitingamount of tripropargyl phosphate.

Extensive testing of tripropargyl phosphate as an agent in an acidsolution for preventing or decreasing the attack on a base metal whilebeing subjected to metal-cleaning or scale removal operations, haveindicated a lower weight loss occurs as a result of acid corrosion withtripropargyl phosphate as compared with other commercially acceptablecorrosion inhibitors. A further advantage of tripropargyl phosphate as acomponent in a corrosion inhibiting composition resides in its apparenteffectiveness in preventing or lessening hydrogen embrittlement.

The results of the testing indicated above of tripropargyl phosphate ascompared with other commercially acceptable corrosion inhibitors isreflected in the subsequent "ice Table I with various acid solutionsbased on 2.5 weight percent of additive based on percent of acidemployed. In comparing the properties and advantages of tripropargylphosphate as an additive component in acidcleaning solutions with othercommercially acceptable inhibitors with respect to stability andinhibiting of corrosion and hydrogen embrittlement, the following testswere performed:

Hydrogen embrittlement inhibition The method employed, essentially thatof C. A. Zapffe et al., described in Metals Technology, January (1946),pp. 281-312 (discontinued 1948, now issued as Journal of Metals), treatsstainless steel wire A181 440 C., 0.060 in diameter in the pickling acidfor 15 minutes at 77 C. then bends the wire around a pin until breakageoccurs. The angle of breakage or bend tolerance is an indication ofhydrogen embrittlement inhibition, the higher values indicating greaterinhibition activity.

Corrosion inhibition The test method employed to measure theeffectiveness of test compounds as corrosion inhibitors is based on theweight loss which occurs after a test panel is immersed in a test acidsolution for a given period of time. In the tests conducted, the resultsof which are reported below, 1" x 2" panels of mild steel (1010 type)are immersed in 10 percent hydrochloric and sulfuric acids testsolutions containing 0.25 weight percent (2.5 weight percent based on100 percent acid) of the test corrosion inhibitors for two hours at 77C. The panels are then removed from the solutions, flushed, dried andmeasured by weight loss.

Stability The stability of tripropargyl phosphate and other additiveswith regard to color and precipitation in concentrated hydrochloric acidwas carried out by adding from 0.5 to 1.0 weight percent of theadditives to the acid solution with or Without mixing. The testsolutions were examined visibly over a period of time and changes incolor and composition recorded.

The following Table I reflects the data obtained in tests of variouscorrosion inhibitors including tripropargyl phosphate. The table alsoreflects the values obtained with tests of solutions which did notcontain any corrosion inhibitor.

TABLE I Hydrogen Corrosion Mild Embrittlement, Steel, Percent TestInhibitor Break Angle Wt. Loss 13% 10% 10% 10% H 804 lIOl H 804 HCl None45 63 4. 3 11. 4 Propargyl AlcohoL 64 109 2. 0 0. 09 Propargyl Alcoholplus 1.98 moles of Ethylene Oxide 51 103 1. 9 O. 4 (CH COHzOCHzzCHOH- 6893 5.6 0.3 Glycidyl Ether of Polymerized Propargyl AlcohoL 50 97 3.1 0.6Tripropargyl Phosphate. 73 106 0.5 0. 1 CH CCH OCI-IQIHOH 74 109 1.7 0.3

OH CCH OCILCHOH 63 103 2.0 03

VCIIECCHTQNIICIIQCIIQOII 47 94 13.2 0.8 Ant-.iratc 3482 1 41 42 0. 05 0.4 Blank Untreated i 101 101 1 A mixture of aromatic amines withpropargyl alcohol.

as stabilizing additives for analytical grade 37 percent hydrochloricacid.

TABLE IL-STABILIZATION OF ANALYTICAL GRADE 37% H01 WITH PROPARGYLALCOHOL DERIVATIVES [Time, days] Ex. No. Chemicals Added 1 2 0.5%Tripropar yl 1 Phosphate Clear and colorless No change.. No change. Reeat oil 2 do do Do. 0.5 0 Glycidyl Ether of Polymerized Pro- Darkensslightly do Do.

pargyl Alcohol. 0.5% Dipropargyloxymethyl Methanol do D0. 1%CHECCHZSCHQCHQOH 1% CHECCH2OCHCH(C H)OH 1% CHECCHZOCHZOH(CH3)OH 1%Antarate 3481 No change No change.

Ex. N0. 3 4 5 6 7 8 No change No change No change No change No change Nochange. do .do do "do .do do d0. Slightly cloudy --.d0 -d0 Slight pptSlight ppt.,

' yellow S0111. 4.- rln dn do do .do Do. 5 Darker Cloudy and very Ppt.1'orming .do No change Much Ppt.,

dark. very dark. 6 do Ppt. forming No change d0 do Pptinln dark so 7 dodo do do Do.-- 8 No change No change.-. -do do Very dark but no ppt.

1 Still clear and colorless after 23 days. 2 Still clear and colorlessafter 16 days.

The amount of tripropargyl phosphate to be employed to be effective inminimizing corrosion and hydrogen 1' Example ].--Preparati0n oftripropargyl phosphate There was charged 168.0 grams (3 moles) propargylalcohol, 404.8 grams (4 moles) triethyl amine, and 500 ccs. dry ether.At 5 to C. there was added dropwise a solution of 153.0 grams (1 mole)phosphorus oxychloride in 100 ccs. dry ether in 1.5 hours. The mixturewas stirred one hour longer at 10 to 0 C. The amine hydrochloride wasremoved by filtration and the ether removed under aspiration vacuum. Theresidue was then heated to 50 C. under 0.2 mm. Hg pressure.

This residue was then heated to 70 C., with stirring, with 150 ml.distilled water. To this was added 150 ccs. benzene and the phasesseparated. The aqueous phase was extracted with two 100 cc. portions ofbenzene. The organic layers were combined and dried overnight at roomtemperature over Drierite. The desiccant was removed by gravityfiltration and the benzene removed under aspirator vacuum. The residuewas heated to 60 C. under 0.2 mm. Hg pressure. There remained 52.6 gramsof a straw-yellow oil having a boiling point of Ill-113 C. at 0.08 mm.of Hg pressure and a refractive index (n of 1.46801.4684.

Calcd Found Percent C 51.0 52. 38 Percent lI 4. 25 5. 42 Percent P 14.613.41; 13.48 Acetylenic Hydrogen (mole/g.) 0.01415 0. 01408 satisfactoryas corrosion inhibitors. but can readily be purified and a good grade ofcorrosion inhibitor obtained by distillation under reduced pressures inthe presence of a small amount of a free radical inhibitor, i.e.,p-terincluded in the purview of the application and the spirit and scopeof the appended claims.

What is claimed is:

1. A metal cleaning composition consisting essentially of an acidselected from the group consisting of hydrochloric, sulfuric,phosphoric, hydrofluoric, citric, oxalic and sulfamic acids in an amountsufficient to clean metal, and 0.5 to 5 weight percent, based on percentacid, of tripropargyl phosphate.

2. The composition of claim 1 wherein the acid is sulfamic acid.

3. The composition of claim 1 wherein the acid is oxalic acid.

4. The composition of claim 1 wherein the acid is citric acid.

5. The composition of claim 1 wherein the acid is hydrofluoric acid.

6. The composition of claim 1 wherein the acid is phosphoric acid.

7. The composition of claim 1 wherein the acid is sulfuric acid.

8. The composition of claim 1 wherein the acid is hydrochloric acid.

9. As a corrosion inhibitor, tripropargyl phosphate.

References Cited by the Examiner LEON D. ROSDOL, Primary Examiner.JULIUS GREENWALD, Examiner.

W. E. SCHULZ, Assistant Examiner.

1. A METAL CLEANING COMPOSITION CONSISTING ESSENTIALLY OF AN ACIDSELECTED FROM THE GROUP CONSISTING OF HYDROCHLORIC, SULFURIC,PHOSPHORIC, HYDROFLUORIC, CITRIC, OXALIC AND SULFAMIC ACIDS IN AN AMOUNTSUFFICIENT TO CLEAN METAL, AND 0.5 TO 5 WEIGHT PERCENT, BASED ON 100PERCENT ACID, OF TRIPROARGYL PHOSPHATE.